in final render it remains visible from the start! The castle isn't supposed to show in the beginning
The eye icon controls the viewport visibility. The render visibility is controlled by the camera icon. Both of them can be keyframed independently of each other. This way you can have an object visible while you model, e.g. to make sure it doesn't intersect other objects, while hiding it in the render, or hide an object in the viewport, to make otherwise obscured objects easier to edit, while having it show up in the render. The screenshot below is from Blender 2.79, and in 2.8 it is slightly different, but similar enough that this image should suffice for both versions.